qbe-rs VS simplelanguage

> I think it uses a different backend than LLVM

harec uses https://c9x.me/compile/

Have you considered QBE?

I really hope other new projects (like QBE) can really grow and become widely used

I really liked targetting QBE (https://c9x.me/compile/) as an IR, as it gave me lots of back-end optimisations for free 😊.

There is: QBE.

You might be underestimating the accuracy of the CPU models LLVM uses.

For x86, the same data the code generator uses drives llvm-mca[1], which given a loop body can tell you the throughput, latency, and microarchitectural bottlenecks (decoding, ports, dependencies, store forwarding, etc.)—if not always precisely, then still not worse then IACA, the tool written at Intel by people who presumably knew how the CPUs work, unlike LLVM contributors and the rest of us who can only guess and measure. This separately for Haswell, Sandy Bridge, Skylake, etc.; not “x86”.

Now, is this the best model you can get? Not exactly[2], but it’s close enough to not matter. Do we often need machine code to be optimized to that level of detail? Perhaps not[3], and with that in mind you can shave at least a factor of ten off LLVM’s considerable bulk at the cost of 20—30% of performance[4,5]. But if you do want those as well, it seems that the complexity of LLVM is a fair price, or has the right order of magnitude at least.

(Frontend not included, C++ frontend required to bootstrap sold separately, at a similar markup compared to a C-only frontend with somewhat worse ergonomics.)

[1] https://llvm.org/docs/CommandGuide/llvm-mca.html

[2] https://www.uops.info/

[3] https://briancallahan.net/blog/20211010.html

[4] https://c9x.me/compile/

[5] https://drewdevault.com/talks/qbe.html

You can try buildling you own backend like llvm. A good example or starting point is probably QBE since it is extremely small but very functional.

How big is the whole backend? I've heard that it is small but I wanted to compare it to QBE which is around 8 KLoC and it is quite interesting too.

That sort of stuff is easy to do with Truffle (which, ironically, lets you define a language using what they call the "truffle dsl").

The SimpleLanguage tutorial language has a bigint style number scheme with efficient optimization:

https://github.com/graalvm/simplelanguage/blob/master/langua...

Truffle has no opinion on how you parse the sources. It cares about how you execute them from an intermediate Truffle guided representation produced by the parser.

In other words antlr and truffle are a great fit. We even use this pairing for our example language simplelanguage.

https://github.com/graalvm/simplelanguage

Do you have any feedback on how we could improve the docs? If so, please let us know!

I believe the easiest way to start a new Truffle language implementation is to fork SimpleLanguage [1] and turn it into your language. Did you try to do that?

[1] https://github.com/graalvm/simplelanguage

Finally, I would suggest you to take a look at the Truffle/GraalVM ecosystem(https://www.graalvm.org/graalvm-as-a-platform/language-implementation-framework/). The documentation is not exactly very elaborate, but a few good resources are Mumbler(http://cesquivias.github.io/blog/2014/10/13/writing-a-language-in-truffle-part-1-a-simple-slow-interpreter/#mumbler-language), SimpleLanguage(https://github.com/graalvm/simplelanguage), and (https://www.endoflineblog.com/graal-truffle-tutorial-part-4-parsing-and-the-trufflelanguage-class).